System for supplying gaseous material to a flow of liquid

ABSTRACT

A chlorinating system wherein chlorine gas is supplied successively from a pair of cylinders to a flow of water. The system includes, in addition to means for injecting chlorine into the water flow and means for controlling the rate of delivery of chlorine to the injecting means, a pair of pressure-reducing valve units respectively mounted on the valve outlets of the two cylinders and connected through conduits to a common gas passage upstream of the controlling means. Each valve unit includes a valve for discharging chlorine, from the cylinder on which it is mounted, into the system at a reduced pressure; a pressureresponsive diaphragm for moving the valve between closed and open positions; and a latch for holding the diaphragm in a position at which the valve is closed. When one valve is open, discharging chlorine into the system from its associated cylinder, the other valve is closed. Depletion of chlorine in the first cylinder causes a decrease in system pressure which, communicated to the second valve unit, releases the diaphragm of the second valve unit from its latch to open the valve of this second unit, thus initiating discharge of chlorine into the system from the second cylinder as the first cylinder becomes exhausted.

United States Patent [72] Inventors Richard W. Jordan West Caldwell; William C. Conkling, Essex Falls, both of, NJ.

[21] Appl. No. 812,641

[22] Filed Apr. 2, 1969 [45] Patented Sept. 14, 1971 [73] Assignee Pennwalt Corporation [54] SYSTEM FOR SUPPLYING GASEOUS MATERIAL Primary Examinerl .averne D, Geiger Assistant Examiner-David J. Zobkiw Attorneys-Robert S. Dunham, P. E. Henninger, Lester W. Clark, Gerald W. Griffin, Thomas F. Moran, Howard .1. Churchill, R. Bradlee Boal, Christopher C. Dunham and Robert Scobey ABSTRACT: A chlorinating system wherein chlorine gas is supplied successively from a pair of cylinders to a flow of water. The system includes, in addition to means for injecting chlorine into the water flow and means for controlling the rate of delivery of chlorine to the injecting means, a pair of pressure-reducing valve units respectively mounted on the valve outlets of the two cylinders and connected through conduits to a common gas passage upstream of the controlling means. Each valve unit includes a valve for discharging chlorine, from the cylinder on which it is mounted, into the system at a reduced pressure; a pressure-responsive diaphragm for moving the valve between closed and open positions; and a latch for holding the diaphragm in a position at which the valve is closed. When one valve is open, discharging chlorine into the system from its associated cylinder, the other valve is closed.

SHEET 2 OF 5 5Q wk PATENTED SEP] 41% SHEET 3 OF 5 PATENTED saw 41971 3 604,445

SHEET 5 [IF 5 SYSTEM FOR SUPPLYING GASEOUS MATERIAL TO A FLOW OF LIQUID BACKGROUND OF THE INVENTION This invention relates to systems for supplying gaseousmaterial at a controlled rate from supply cylinders to a flow of liquid. in an important specific aspect, it is directed to chlorinating systems.

Chlorination, as employed in conditioning contaminated water for human use or other purposes, is commonly effected by introducing gaseous chlorine from a supply cylinder to a minor flow of water and returning the resultant chlorine solution to the major flow or body of water to be treated, the rate of chlorine supply being carefully controlled to maintain the chlorine content of the treated water safely below a toxic level but sufficiently high to accomplish the desired treatment. Typically, a chlorinating system includes an injector having a venturi or like passage for the minor flow of water with an opening through which chlorine gas is drawn into the water by suction created by the water flow. The system defines a continuous path for gas flow from the supply cylinder to the injector opening, and incorporates suitable instrumentalities for controlling the rate of chlorine flow along this path.

In present day commercial practice, chlorine for such use is supplied at elevated pressure in cylinders each containing a standard amount (eg 100 or 150 lbs.) of chlorine and each having a valve outlet for discharge of chlorine. For convenience, safety and other reasons, it is often desired to position the injector and/or other parts of the chlorinating system at localities more or less remote from the supply cylinder, and hence to conduct the chlorine discharged from the cylinder along a corresponding extended path to such localities. Chlorinating systems are known which include means for reducing the pressure of the discharged chlorine at or adjacent to the cylinder valve outlet, to enable the chlorine to be conducted over extended distances without use of the relatively costly high-pressure tubing that would be needed to conduct the chlorine at the elevated pressure obtaining in the supply cylinder, and without requiring special provision for avoidance of chlorine condensation such as would tend to occur if the chlorine were conducted at that elevated pressure and at ordinary room temperature over a substantial distance. Another feature sometimes included in known systems is a valve which automatically closes the inlet end of the system g'as path, in response to cessation of pressure of chlorine emerging from the cylinder valve outlet, so as to prevent communication between the system and the ambient atmosphere through such inlet end when an exhausted supply cylinder is removed for replacement with a fresh cylinder; this valve may be arranged to reopen automatically in response to resumption of chlorine pressure, i.e., from the fresh cylinder.

A disadvantage of the known chlorinating systems referred to above is that they require replacement of the supply cylinder each time one supply cylinder becomes exhausted. Cylinder replacement necessitates interruption of the operation of the system, and also involves substantial maintenance attention on the part of operating personnel, in detaching from the exhausted cylinder the system elements mounted thereon, which may be more or less complex, heavy and delicate; physically removing the exhausted cylinder, and moving the fresh cylinder into position; remounting the system elements on the fresh cylinder, and restarting the system. A further problem is that if the system is inadvertently permitted to continue to operate with an exhausted cylinder, owing to lack of attention by operating personnel, the cessation of chlorine supply from the system results in a failure of proper water treatment and may create a possible health hazard.

it would be desirable, in a chlorinating system, to achieve uninterrupted continuity of system operation, i.e., to enable replacement of chlorine supply cylinders without interrupting the chlorinating treatment effected by the system. it would also be desirable to reduce the frequency of required maintenance attention for replacement of cylinders, or in other words to enable the system to operate without such attention for periods significantly longer than the period corresponding to the chlorine capacity of a single supply cylinder. Such extension of the period between cylinder-replacing operations would, in at least many cases, enable cylinder replacement to be so scheduled as to minimize or entirely eliminate the neces sity of replacing cylinders at inconvenient times, such as night hours, and in addition would lessen the likelihood of failure of proper chlorinating treatment resulting from inadvertent delay in replacing an exhausted cylinder.

SUMMARY OF THE lNVENTION An object of the present invention is to provide a system for supplying gaseous material such as chlorine to a flow of liquid in a continuous manner, requiring no interruption for replacement of an exhausted supply cylinder of the gaseous material. Another object is to provide such a system which is operable without replacement of supply cylinders for a period advantageously longer than that corresponding to the capacity of a single supply cylinder, to reduce the required frequency of maintenance attention for cylinder replacement and to enable convenient scheduling of such maintenance. A further object is to provide such a system wherein the gas is supplied in succession from two conventional supply cylinders. A still further object is to provide such a system wherein supply of gas from the second cylinder is initiated automatically upon, and in response to, exhaustion of the first cylinder. Yet another object is to provide such a system, including separate gas inlets for connection to each cylinder, each inlet having a valve for closing the inlet upon cessation of pressure of gas emerging from the cylinder, and incorporating new and improved means for automatically reopening this valve upon resumption of such gas pressure.

A further object is to provide a pressure-reducing valve unit assembly for a gas supply system, mountable on the valve outlet of a gas supply cylinder, and normally closed but adapted to open automatically, to effect discharge of gas from the cylinder at reduced pressure, in response to decrease in system pressure resulting from exhaustion of another gas supply cylinder connected in the system. Still another object is to provide a valve unit assembly, mountable on the valve outlet of a gas supply cylinder and closable in response to cessa' tion of pressure of emerging gas from the cylinder, incorporating new and improved means for reopening the valve unit in response to resumption of emergent gas pressure.

To these and other ends, the present invention broadly contemplates the provision of a system for supplying gaseous material to a flow of liquid from supply cylinders containing the gaseous material at elevated pressure, including the combination, with injector means for introducing a flow of the gaseous material to the liquid flow and control means for supplying a flow of the gaseous material to the injector means at a controlled rate, of a pair of valve means respectively adapted to be connected to a pair of the cylinders for effecting discharge of the gaseous material at reduced pressure into the system from the cylinders to which they are respectively connected, the valve means each being closable to prevent such discharge, and being separately and successively openable to effect such discharge from the two cylinders in succession; and a pair of conduits respectively connecting the two valve means to an inlet passage of the control means for delivering the gaseous material, discharged through the valve means, to the control means.

In this arrangement of elements, e.g., as embodied in a chlorinating system, with the two valve means respectively connected to conventional valve outlets of two chlorine supply cylinders, and the valve outlets of both cylinders open, discharge of chlorine from the cylinders into the system is under control of the two valve means. Initially, one of the valve means is open and the other is closed, so that chlorine discharges into the system only from the cylinder connected to the open one of the valve means. As this first cylinder becomes exhausted, the second valve means is opened, and chlorine continues to be supplied to the system, i.e., from the second cylinder. While the second cylinder is discharging, the first cylinder may be replaced without interruption of the chlorinating operation of the system, and as the second cylinder becomes exhausted, the valve means connected to the fresh replacement for the first cylinder may be opened to continue the chlorinating operation. Also, since the first (exhausted) cylinder need not be replaced until the second cylinder approaches exhaustion, the system is enabled to operate without replacement of cylinders for a period very significantly longer than (indeed, almost twice as long as) that corresponding to the chlorine capacity of a single cylinder. Thus, both cylinders may be replaced within a relatively short interval, and the system may then be allowed to operate with chlorine supplied from the two fresh cylinders in succession (with opening of the second valve means as the first cylinder becomes exhausted), the cylinder-replacing operation being deferred until the second cylinder again approaches exhaustion, facilitating convenient scheduling of the cylinderreplacing operation.

As a further particular feature of the invention, each of the two valve means of the system may comprise a valve unit mountable on a gas supply cylinder, and including a valve which prevents discharge of gas from the cylinder when closed, and effects discharge of gas from the cylinder at a reduced pressure when open; and valve control means, normally holding the valve closed, for opening the valve in response to a decrease in gas pressure within the system. In operation of the described system, with one supply cylinder discharging gas into the system through the valve unit mounted thereon, depletion of gas in the discharging cylinder causes a decrease in system gas pressure, which actuates the valve control means of the second valve unit (mounted on the second cylinder) to open the valve of the second unit and thereby to initiate discharge of gas into the system from the second cylinder. The switchover from the first cylinder to the second cylinder, to provide supply of gas from the two cylinders in succession, is thus effected automatically upon exhaustion of the first cylinder, without any attention by operating personnel. Automatic switchover from the second cylinder back to a fresh first cylinder is effected in the same manner upon exhaustion of the second cylinder.

Each valve control means may include an element such as a flexible diaphragm, exposed on opposite sides to system pressure and to a substantially constant higher pressure (e.g., atmospheric pressure), and movable in response to changes in the differential between these pressures. Each valve includes, and is closed by, a movable stem so operated by the diaphragm that diaphragm movement in response to increasing pressure differential (resulting from decreasing system pressure) displaces the stem to open the valve. Each valve control means further includes a latching means for exerting on the diaphragm a finite restraining force, holding the diaphragm in a position at which the valve stem closes the valve, against the force of the pressure differential acting on the diaphragm. The decrease in system pressure resulting from depletion of gas in a supply cylinder discharging through one valve unit increases the pressure differential acting on the valve control diaphragm of the second valve unit sufficiently to overcome the restraining force of its associated latching means, and thereby to move the diaphragm and valve stem to a position at which the valve of the second unit is open.

Each valve unit may include a second valve, having a stern carried by the diaphragm, and disposed downstream of the first valve in a gas inlet passage. The second valve is arranged to be closed by movement of the diaphragm beyond the position at which the first valve opens, the pressure differential urging the diaphragm to displace the stem of the second valve toward closed position. The valve control arrangement may be such that upon movement of the first valve stem to open position, with normal supply of chlorine to the system, the pressure differential is sufficiently small so that a biasing force acting on the diaphragm prevents further movement of the diaphragm to the position closing the second valve; but upon cessation of chlorine supply, and consequent increase in pressure differential across the diaphragm, the stem of the second valve is moved to its closed position, enabling an exhausted cylinder to be removed from the valve unit without opening the system to communication with the ambient atmosphere through the valve unit, i.e., under conditions in which there is no chlorine supply to the system.

As a further feature of the invention, each valve unit may include a supplementary bypass valve providing a gas path bypassing the second valve and having a movable element biased to closure against atmospheric pressure but openable in response to the elevated pressure of gas emerging from a supply cylinder, to conduct such gas to the low-pressure side of the diaphragm for reopening the second valve, i.e., upon connection of the valve unit to a fresh cylinder, under certain particular operating conditions. The several valves are so arranged that as the second valve reopens, the pressure differential across the movable element of the bypass valve decreases sufficiently to permit the bypass valve to close again.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view of a chlorinating system embodying the present invention in a particular form;

FIG. 2 is a longitudinal sectional view of one valve unit of the system of FIG. 1;

FIG. 3 is a similar view of an alternative form of valve unit structure adapted for use in the system of FIG. 1;

FIG. 4 is a sectional view of the alternative form of valve unit taken along the line 44 of FIG. 3;

FIG. 5 is an end elevational view of the control unit of the system of FIG. 1;

FIG. 6 is an opposite end elevational view of the control unit of FIG. 5;

FIG. 7 is a sectional view of the control unit, taken along the line 7-7 of FIG. 5;

FIG. 8 is another sectional view of the control unit, taken along the line 8-8 of FIG. 5;

FIG. 9 is a fragmentary sectional view of the control unit, taken along the line 99 of FIG. 5; and

FIG. 10 is an elevational view of a modified chlorinating system also embodying the invention.

DETAILED DESCRIPTION Referring first to FIG. 1, the invention is shown as embodied in a chlorinating system 10 arranged to supply gaseous chlorine at a controlled rate to a minor flow of water, in which the chlorine is dissolved and carried to a major flow or body of water to be treated. Chlorine is supplied to the system from conventional commercial supply cylinders each initially containing a standard amount (e.g., lbs.) of chlorine at superatmospheric pressure, and each having a conventional valve outlet which is openable to discharge chlorine from the cylinder. As illustrated, two such cylinders (respectively designated 11 and 12) are connected to the system, through their respective valve outlets l4 and 15, which are positioned at the upper ends of the vertically oriented cylinders.

The system 10 includes a pair of pressure-reducing and shutoff valve units 17 and 18 respectively mounted on the valve outlets l4 and 15 of the two cylinders 11 and 12. Each of these units has a valve for shutting off discharge of chlorine from the cylinder on which it is mounted, and for effecting discharge of chlorine from the cylinder at a reduced, subatmospheric pressure when open. In operation of the system, the valve outlets l4 and 15 of the two cylinders are both turned to open position so that discharge of chlorine from both cylinders is solely under control of the respective valve units 17 and 18, which are operated to effect discharge of chlorine into the system from the two cylinders in succession.

The system also includes a control unit connected to the two valve units 17 and 18 by separate conduits comprising lengths of flexible tubing, respectively designated 21 and 22, for conducting gaseous chlorine at subatmospheric pressure from the valve units to the control unit. Both conduits open into a common gas passage through the control unit, in which there are provided suitable instrumentalities for controlling the rate of chlorine flow, to provide feed of chlorine at such controlled rate through an outlet 23 of the control unit.

The system further includes an injector unit 25 which receives the controlled flow of chlorine from the control unit outlet 23 through a conduit comprising a further length of flexible tubing 26. The aforementioned minor flow of water is conducted through the injector unit, and the gaseous chlorine supplied by the system is introduced to the water flow within the injector. Valve units 17 and 18, conduits 21 and 22, control unit 20, conduit 26, and injector unit 25 together constitute a continuous path for flow of gaseous chlorine at subatmospheric pressure from the supply cylinders 11 and 12 into the minor flow of water. From the injector unit, the chlorinecontaining minor flow of water is conducted (e.g., in conventional manner, not illustrated) to a major flow or body of water to be treated, for supply of chlorine thereto, in accordance with conventional chlorinating practice.

The injector unit 25 includes a rigid housing 23 which defines a valve chamber 29 in its upper portion and an axially horizontal water flow passage 30 in its lower portion. Chamber 29 communicates with passage 30 through a port 31. A water inlet nozzle 32 and a water outlet tailpiece 33 are respectively threadedly mounted in opposite ends of the passage 30. Each of these elements 32 and 33 has an axially horizontal bore for conducting a flow of water, the bore of nozzle 32 tapering inwardly in a downstream direction and the bore of tailpiece 33 tapering outwardly in a downstream direction. Within passage 30, the facing ends of the nozzle and tailpiece are disposed in slightly space relation to define a gap 34 between them, and their respective bore openings are in register, so that a flow of water entering the injector unit through the nozzle bore is directed across the gap 34 and into the tailpiece bore.

The chamber 29 contains a check valve 35 comprising a peripherally supported flexible diaphragm 36 extending horizontally across the chamber; a valve seat disc assembly 37 carried by the diaphragm, defining a central valve aperture 38 through the diaphragm; a fixed valve stem 39 mounted in and projecting downwardly from the top wall of housing 28 to engage the upper surface of valve seat disc assembly 37 for closing the aperture 38; and a helical spring 40, under compression between the lower surface of disc assembly 37 and a subjacent portion of housing 28, for biasing the diaphragm and disc assembly upwardly into valve-closing engagement with stem 39. The chlorine gas conduit 26 opens into chamber 29 above the diaphragm 36, through a fitting 41 threaded in the top wall of the housing, while port 31 opens into chamber below the diaphragm, so that fluid passing between conduit 26 and port 31 must traverse the valve aperture 37; thus the check valve 35 controls flow of fluid between the latter conduit and port.

Passage of a flow of water from nozzle 32 to tailpiece 33 creates suction at the gap 34, which draws the diaphragm 36 downwardly against the force of spring to open the check valve 35 and maintain the valve open as long as the water flow continues. This suction, providing a negative pressure or vacuum in the system, draws gaseous chlorine through the system from the discharging supply cylinder 11 or 12 to the injector unit, and through chamber 29, port 31, and passage 30 in the injector unit to the gap 34, where the chlorine is introduced to and mixed with the water flow. If the water flow is interrupted or shut off, the suction ceases, permitting spring 40 to close valve 35 and thus to prevent flow of chlorine beyond the valve 35, or in other words to prevent discharge of chlorine from the system through the injector unit when there is no water flow. Also, if water from passage 30 begins to flood the injector unit, the flooding condition closes the check valve 35 and prevents water from flooding the chlorinating system upstream of the injector unit.

The structure of the control unit 20, which as stated regulates the feed of chlorine to the injector unit, is illustrated in detail in FIGS. 5-9. As there shown, the control unit includes a rigid housing 48 formed of plural housing sections secured together by screws 49. In its lower portion, the housing structure defines a gas inlet passage 50, into which the two conduits 21 and 22 open (through fittings 51 and 52 threaded in the bottom wall of housing 48) for delivery of gaseous chlorine from the supply cylinders 11 and 12. In its upper portion, the housing structure defines a further gas passage 53, in which is mounted an adjustable metering orifice 54 (hereinafter further described) for controlling the rate of chlorine flow through passage 53.

Gas flows from passage 52 upwardly to passage 53 through an axially vertical, downwardly tapering transparent meter tube 55, which is mounted on housing 48 so as to be visible from the exterior of the control unit. The lower end of tube 55 communicates with passage 50, and the upper end of the tube communicates with passage 53 upstream of the metering orifice 54. The tube 55 contains a ball float 56, which cooperates with the tube to constitute a variable area flowmeter. In accordance with well-known principles of variable area flowmeter operation, gas flowing upwardly through tube 55 elevates the ball float in the tube to a level determined by the instantaneous gas flow rate. A suitably calibrated scale 57, marked on the surface of tube 55, enables the observed position of float 56 in the tube at any instant to be read as a measure of flow rate.

In the form shown in FIG. 7, the structure defining adjustable metering orifice 54 comprises an orifice member 60 fixedly mounted in the passage 53 and having a circular aperture, and a V-notch plug 61 which projects through and fits snugly within the aperture of member 60. Plug 61 extends outwardly from passage 53 through the adjacent housing wall, and at its outer end is fixedly secured to a knob 62; this knob is threadedly mounted on a projecting sleeve 63 on the exterior of housing 48, in such manner that axial displacement of the plug relative to the orifice member may be efi'ected by manually turning the knob to vary the extent of threaded engagement thereof with the sleeve. The portion of plug 61 extending through the aperture of member 60 bears a longitudinally extending V-notch or groove 64 which varies progressively in depth and width toward the inner end of the plug, the walls of the notch cooperating with member 60 to define the orifice 54 through which the gas flow passes. Since the notch dimensions vary longitudinally along the plug, axial displacement of the plug relative to member 60 varies the area of orifice 54 and hence varies the rate of gas flow therethrough. As illustrated in FIGS. 5 and 7, the knob 62 is positioned immediately above the visible portion of meter tube 55; gas flow rate is adjusted to a desired value by turning the knob to vary the flow rate while observing the float 56in tube 55, until the float reaches the level representative of such flow rate value.

Downstream of the metering orifice 54, passage 53 communicates through a port 66 (FIG. 7) with a valve chamber 67 in housing 48. Within the chamber 67 is disposed a differential pressure valve 68 (hereinafter further described) including an annular valve seat 70, mounted in the right-hand wall of chamber 67 as seen in FIG. 8. The seat 70 defines a valve port 71, through which chlorine passes from chamber 67, under control of valve 68, to a gas outlet passage 73 formed in housing 48 ad leading to the control unit gas outlet 23. Conduit 26 is connected to outlet 23, which comprises a fitting threaded in housing 48 at the outlet end of passage 73. Thus inlet passage 50, meter tube 55, passage 53, port 66, chamber 67, port 71 and passage 73 define a continuous path through the control unit 20 for flow of chlorine gas from conduit 21 or 22 to conduit 26; and gas advancing along this path successively traverses the flowmeter, metering orifice 54, and differential pressure valve 68.

The differential pressure valve 68 (best seen in FIG. 8) further includes a peripherally supported flexible diaphragm 75 carrying a central backing disc assembly 76, and extending vertically across chamber 67; a valve stem 77, carried by and projecting from the right-hand side of disc assembly 76 toward seat 70; and cooperating with the seat to define a variable area annular space for gas flow through port 71; and a helical biasing spring 78, under compression between the disc assembly 76 and the right-hand wall of chamber 67, for urging the diaphragm and stem 77 away from seat 70, i.e., toward valveopening position. Both port 66 and valve port 71 open into chamber 67 on the right-hand side of diaphragm 75, which inlet passage 50 communicates with chamber 67 on the lefthand side of diaphragm 75 through a passageway 79 (FIG. 7), so that opposite sides of the diaphragm 75 are acted on by gas pressures respectively upstream and downstream of the metering orifice 54. In this arrangement, increase in pressure drop across the metering orifice moves diaphragm 75 (and hence stem 77) to the right, reducing the opening of valve 68 so as to decrease outflow of gas from the downstream side of orifice 54, while decrease in pressure drop across orifice 54 has an opposite effect on valve 68. Thus valve 68 functions to counteract any change in pressure drop across the metering orifice, and thereby to maintain this pressure drop at a substantially constant value regardless of pressure changes elsewhere in the system (e. g., changes in vacuum resulting from water flow rate variations in the injector unit), as desired for maintenance of a precisely controlled rate of chlorine gas feed through the metering orifice.

The housing 48 also defines a further valve chamber 80, to the left of chamber 67 as seen in FIGS. 7 and 8, containing a pressure relief valve 81. Gas inlet passage 50 communicates with the right-hand side of chamber 80 through a branch 82 of the aforementioned passage 79, while the left-hand side of chamber 80 is open to the atmosphere through a vent conduit 84 which communicates with chamber 80 through a fitting 85 threaded in the outlet end of a passage 86 through the hous- The relief valve 81 includes a peripherally supported flexible diaphragm 88, extending vertically across the chamber 80 to separate the left and right sides thereof and bearing a central backing disc assembly 89 which has a valve port 90 opening through its central portion. The left and right sides of this diaphragm are respectively acted on by atmospheric pressure and by chlorine gas pressure from passage 50, creating a pressure differential that normally urges the diaphragm to the right. A horizontal shaft 91 extends, with clearance, through port 90, and to the left of port 90 bears a rigid disc 93 which is positioned to engage the left-hand wall 94 of chamber 80 to limit leftward movement of the shaft. To the right of diaphragm 88, the shaft is enlarged to form a valve stem 96 for closing valve port 90. A helical biasing spring 98, under compression between shaft disc 93 and the membrane disc assembly 89, urges the assembly 89 to the right into valve-closing engagement with stem 96. Under normal operating conditions, the differential between the atmospheric pressure and chlorine gas pressure (normally subatmospheric), acting across diaphragm 88, cooperates with spring 98 to hold the valve 81 closed. However, in the event of excessive buildup of chlorine in the system, the resultant elevated chlorine pressure acting on the right-hand side of diaphragm 88 moves the diaphragm to the left, and (when shaft disc 93 abuts wall 94 to arrest leftward shaft movement) moves the disc assembly 89 leftward in relation to stem 96, opening the valve port 91. Chlorine then escapes from the system through port 91, the left-hand side of chamber 80, and vent conduit 84 to the air, relieving the chlorine pressure buildup in the system.

To the left ofdisc 93, the shaft 91 projects through, and outwardly beyond, a bore 100 in the chamber wall 94. At one side of the shaft end, outwardly of wall 94, is disposed an indicator element 102 having a surface curved about a horizontal axis,

and rotatably mounted on housing 48 by means of a rod 103 i for angular movement about that axis. An eccentrically disposed lug 104 projecting from the side of the indicator 102 engages an annular groove 105 in the shaft end so that leftward and rightward axial movement of the shaft rotates the indicator between two different angular positions. To the right of stem 96 within chamber 80, the shaft 91 bears an enlarged head 107; a biasing spring 108, under compression between head 107 and the righthand wall of chamber 80, urges shaft 91 to the left. Under conditions of normal chlorine supply to the system, the force of spring 108 holds the shaft in a leftward position and maintains the indicator 102 in a first angular position. However, upon cessation or exhaustion of chlorine supply to the system, the resultant increase in pressure differential acting to the right across diaphragm 88 forces the diaphragm to the right, carrying the shaft with it (because of its engagement with stem 96), and thus turns the indicator 102 to a second angular position.

A limited area of the indicator surface is visible through a window 110 in a face plate 111 mounted on housing 48 outwardly of the indicator and adjacent to meter tube 55. Turning of the indicator between its first and second positions exposes two different portions of the indicator surface to view through the window; these two surface portions bear respectively different colors, providing a visual indication through the window of presence or absence of chlorine supply in the system.

The two valve units 17 and 18 in the system of FIG. 1 are identical to each other, and hence their construction and arrangement may be adequately explained by consideration of the unit 18, illustrated in detail in FIG. 2. As there shown, unit 18 includes a yoke 115 for mounting the unit on the valve outlet 15 of supply cylinder 12; a valve housing 116; and a cartridge 117 connecting the yoke to the valve housing.

The yoke is an open, generally rectangular rigid frame adapted to surround the valve outlet 15, and is mounted at one end on the cartridge 117, the inlet end 118 of the cartridge projecting through a bore in the yoke end to engage the valve outlet. Within the yoke, a clamp 120, having opposite side edges slidably engaging guide portions 121 of the yoke sides, is disposed for guided movement toward and away from the cartridge end 118. An adjusting screw 123, extending from the clamp, is threaded through a bore in the end of the yoke remote from the cartridge and terminates in a head 124 outwardly of the yoke. Movement of the clamp within the yoke is effected by turning the screw 123, which holds the clamp fixed in any position to which it is thus moved. When the yoke is mounted on a chlorine supply cylinder 12, the cylinder valve outlet 15 is securely gripped between the clamp and the cartridge inlet end 118, with a gas discharge opening 125 of the valve outlet in register with a gas inlet opening 126 of the cartridge. A gasket 127, e.g., formed of lead, is interposed between the facing surfaces of the valve outlet and the cartridge to provide a gastight seal.

The cartridge 117 is a generally cylindrical rigid body having axially rectilinear central gas passage 129 which extends entirely through the cartridge, from opening 126 in the inlet end 118 to the opposite, outlet end 130 of the cartridge. A central portion of passage 129 is internally threaded, and within this passage portion is threadedly mounted a short cylindrical element 132 having plural longitudinal openings 133 for gas flow. interposed in the passage 129 between inlet opening 126 and element 132 is a glass wool filter 134. Chlorine gas discharged from the valve outlet opening 125 advances along the cartridge passage 129 from the inlet to the outlet end thereof, successively traversing the filter 134 and element 132.

Fixedly mounted in the outlet end of the cartridge passage 129 is a valve seat element 136 having a central port 137 axially aligned with passage 129 and flaring outwardly at its upstream end toward element 132 to form a valve seat 138. A valve member or stem 140 is disposed within passage 129 between element 132 and valve seat 138, and tapers toward the valve seat, for cooperation therewith to constitute a pressure-reducing and shutoff valve 142. Stem 140 is carried on a shaft 143 that extends upstream from the stem through the cartridge passage into a longitudinal opening of element 132 (which serves as a guide for the valve stem shaft), and also extends downstream from the stem through and beyond the valve port 137, the diameter of shaft 143 being smaller than the minimum diameter of port 137 to provide clearance between the shaft and the walls of the port for flow of chlorine gas downstream through the port. A helical spring 145, hearing against and under compression between element 132 and stem 140 within the passage 129, biases the stem toward a valve-closing position in which the stem engages seat 138. The stem 140, when in valve-opening position, cooperates with the valve seat 138 to define a constricted annular orifice which restricts flow of chlorine gas through the valve port when valve 142 is open, i.e., to reduce the pressure of the chlorine gas advancing through the valve port, from the elevated, superatmospheric pressure obtaining in the cylinder to a subatmospheric pressure.

The valve housing 116 comprises a body portion 149 and a cover 150 fixedly secured to the body portion and cooperating therewith to define a valve chamber 152. A flexible diaphragm 154 extends vertically across chamber 152, being clamped between the housing body 149 and the cover 150 so as to be supported at its periphery, the central portion of the diaphragm being displaceable through the chamber. The diaphragm 154 separates the chamber into leftand righthand portions or compartments (as seen in FIG. 2) respectively designated 152a and 152b.

An axially rectilinear valve passage 156 extends horizontally from the center of the left-hand wall 157 of chamber portion 152a through the housing body 149. An internally threaded sleeve 159 formed integrally with the housing body projects toward yoke 115 from the left-hand outer surface of the housing, along a horizontal axis coincident with the axis of passage 156, the internal diameter of sleeve 159 being substantially larger than that of passage 156 and essentially the same as the external diameter of cartridge 117; at its upstream end, passage 156 opens within this sleeve. The portion of the surface of cartridge 117 projecting toward housing 116 from yoke 1-15 bears an external thread, and the threaded portion of the cartridge is received and threadedly mounted within the housing sleeve 159, thus securing the housing, the cartridge, and the yoke together, with the outlet end of the cartridge passage 129 positioned in register with the inlet or upstream end of passage 156. The valve seat member 136 projects for a short distance into the upstream end of passage 156 within the housing, passages 129 and 156 being coaxially aligned. A further valve seat member 160 is mounted in the housing body 149 at the downstream end of passage 156 (i.e., the end of the passage opening into the chamber portion 152a) and defines a valve port 161, substantially larger in diameter than the diameter of orifice 147 but axially aligned with that orifice and with passage 156. At its downstream end, port 161 tapers outwardly (toward chamber portion 152a) to define a valve seat 163 which faces in the opposite direction from valve seat 138. The central portion of the left-hand surface of diaphragm 154 carries a backing disc 164, and centered on this backing disc is a valve member orstem 165 which projects toward and tapers toward the valve seat 163 for cooperation therewith to constitute a backseating valve 167.

The downstream end of shaft 143 projects from the cartridge 117 through passage 156 into chamber 152a in position to be engaged by the nose of the stem 165 carried on diaphragm 154. From the stem 165, a further shaft 170 projects to the right, through and beyond the diaphragm 154, and through the interior of a frustoconical projection 172 formed on the right-hand outer side of housing cover 150. Stem 165, and shaft 143 carrying valve stem .140, are coaxially disposed and so arranged that upon leftward movement of the diaphragm 154, stem 165 engages the downstream (righthand) end of shaft 143 and presses it leftwardly, opening valve 142, against the force of spring 145; and still further leftward movement of the diaphragm brings stem 165 into engagement with seat 163, closing valve 167Rightward movement of the diaphragm opens valve 167, and further rightward movement of the diaphragm releases shaft 143 from engagement by stem 165 so that spring again closes valve 142. Thus opening and closing of both valves 142 and 167 is under control of the diaphragm 154.

A passage 174 extends through the housing body 149 from chamber portion 152a and opens through a sidewall of the housing body. The aforementioned conduit 22 is connected to this passage 174 through a suitable fitting 176 (FIG. 1) threadedly mounted in the outer end of the passage. Thus pressure within the chlorinating system is communicated to the left-hand chamber portion 152a through conduit 22. When both valves 142 and 167 are open, the cartridge passage 126, valve port 137, passage 156, valve port 161, chamber portion 152a passage 174, and fitting 176 define a continuous path for flow of chlorine gas from the supply cylinder valve outlet 15 to conduit 22.

The right-hand portion 152!) of chamber 152 withing hous ing 116 communicates with the ambient atmosphere, (e.g., through a small bleed passage (not shown) in the cover 150. Chamber portion 152b is thus at substantially constant atmospheric pressure, while chamber portion 1520 is, as stated, at the normally subatmospheric pressure obtaining within the system; hence the pressure differential acting across the diaphragm 154 ordinarily urges the diaphragm toward the left as seen in FIG. 2, against the biasing force of spring 145 (communicated to the diaphragm through shaft 143); i.e., this pressure differential urges the diaphragm, and the valve stems 140 and moved by the diaphragm, toward a position at which valve 142 is open and valve 167 is closed.

The spacing between valve stem 140 and the right-hand end of shaft 143 (engaged by stem 165) is sufficiently greater than the spacing between the opposed valve seats 138 and 163 so that when either of the valves 142 and 167 is closed, the other is necessarily open. When the diaphragm is at its furthest right-hand position as seen in FIG. 2, stern 140 engages seat 138 to close valve 142, but stem 165 is spaced rightwardly from seat 163 so that valve 167 is open. When the diaphragm 154 is at its extreme leftward position as seen in FIG. 2, stem 165 engages seat 163 to close valve 167 at the outlet end of passage 156, but stem 140 is spaced to the left of seat 138 so that valve 142 is open, admitting gas to passage 156. Between these two extreme positions of the diaphragm, there is an intermediate position at which stem 140 is spaced slightly to the left of seat 138, and stem 165 is spaced slightly to the right of seat 163, so that both valves 142 and 167 are open to permit flow of chlorine from cartridge passage 129 through passage 156 into the chamber 152a, and thence through passage 174 and conduit 22 into the chlorinating system.

The right-hand portion of shaft 170, extending through the housing cover projection 172, carries a pin 178, axially perpendicular to shaft 170, and extending outwardly of projection 172 on both sides of shaft through slots 179 formed in the projection 172. These slots 179 are of sufficient extent, in the direction of movement of the shaft 170 with diaphragm 154, to permit movement of the pin with the shaft through the full range of diaphragm positions, i.e., from the position at which valve 142 is closed to the position at which valve 167 is closed. The pin 178 is manually displaceable and enables manual movement of the diaphragm and valve stems within the housing 149.

Outwardly of pin 178, shaft 170 carries an indicator sleeve 181, which bears on its outer surface three contiguous bands of respectively different colors, e.g., (reading from left to right) a yellow band 181a, a green band 181b, and a red band 181C. This sleeve 181, moving with shaft 170, is housed within a cap 182 mounted on the outer end of the housing cover projection 172. The cap has a narrow slot 183 so positioned that as the diaphragm moves from the position at which valve 142 is closed through the position at which both valves 142 and 167 are open, to the position at which valve 167 is closed, the yellow, green and red bands of the indicator sleeve are successively carried into register with the slot 183, thus respectively providing visual indications of the three valve positions within the valve unit 18.

As a particular feature of the invention, in the embodiment illustrated in FIG. 2, a permanent magnet 185 is fixedly mounted e.g., cemented) within the housing cover projection 172, with its poles facing into the right-hand chamber portion 152b, i.e., toward the diaphragm 154. Shaft 170 extends slidably through a central bore in this magnet. A backing disc 186, formed of magnetic material, such as a ferrous metal, is fixedly mounted on the right-hand surface of diaphragm 154 in surrounding relation to the shaft 170 so as to face the magnet 185. The poles of magnet 185 attract disc 186, tending to hold the diaphragm 154 at its furthest rightward position against the force of the aforementioned pressure differential acting across the diaphragm, and thus to hold the stern 165 away from engagement with shaft 143 so that spring 145 maintains stem 140 in a position closing valve 142, shutting off discharge of chlorine from the supply cylinder to which the valve unit is connected. In other words, the magnet 185 and magnetic disc 186 cooperate to constitute a latch 187 normally holding the diaphragm 154 in a position at which the valve 142 (controlled by the diaphragm) is closed.

Specifically, the strength of this magnetic latch is such that when chlorine is discharging into the system from supply cylinder 11 through valve unit 17, the latch 187 restrains diaphragm 154 (to maintain the valve 142 of valve unit 18 closed), against the force of the differential between atmospheric pressure acting on the right-hand side of diaphragm 154 and system pressure acting on the left-hand side of diaphragm 154, thereby preventing discharge of chlorine from the supply cylinder 12 on which valve unit 18 is mounted. However, decrease in system pressure resulting from depletion of chlorine supply in the discharging cylinder 11 increases the pressure differential across diaphragm 154 in valve unit 18 sufficiently to release the diaphragm from the restraining force of latch 187 and move the diaphragm to the left, opening valve 142.

By way of further explanation, it will be understood that as long as gas is discharging into the system 10 from cylinder 11 at a normal rate, the pressure within the system (i.e., the pressure communicated to chamber portion 152a through conduit 22 from control unit inlet passage 50) is at a first subatmospheric value. Depletion of chlorine in the discharging cylinder 11, and consequent dropoff of gas supply to the system, causes the system pressure (again, as communicated to chamber portion 152a) to fall to a second and lower subatmospheric value, owing to the continuing suction applied to the system by continuing flow of water through the injector unit 25. As the system pressure falls in chamber portion 152a of valve unit 18, the pressure differential across diaphragm 154 correspondingly rises, because the atmospheric pressure in chamber portion 152b remains substantially constant. Whereas latch 187 is strong enough to hold the diaphragm against the leftward force exerted by the differential between atmospheric pressure and the first-mentioned value of system pressure, it is not strong enough to hold the diaphragm against the greater leftward force of the differential between atmospheric pressure and the second-mentioned lower value of system pressure; hence the system pressure decrease occasioned in chamber portion 152a by depletion of chlorine discharge from cylinder 11 overcomes the restraining force of the magnetic latch in valve unit 18 and moves the diaphragm 154 to the left so as to open the valve 142. Chlorine then begins to discharge into the system from the cylinder 12 on which unit 18 is mounted.

As long as chlorine is discharging into the system through either of the units 17 and 18, the system pressure in chamber compartment 15211 is large enough (i.e., the pressure differential across diaphragm 154 urging the diaphragm to the left is small enough) so that spring 145 restrains the diaphragm against further leftward movement that would close valve 167. However, in the event that both cylinders 11 and 12 become exhausted or are both shut off at their respective valve outlets, terminating all chlorine supply to the system, the resultant decrease in pressure in chamber portion 152a (and the corresponding increase in pressure differential acting to the left across diaphragm 154) moves the diaphragm all the way to the left to close the backseating valve 167. The closure of this valve enables the cylinder to be removed for replacement with a fresh cylinder without danger that air will enter the system through the valve unit 18.

From the foregoing it will be understood that the pressure differential across diaphragm 154 required to close valve 167 is substantially higher than that required to maintain valve 142 open (i.e., once the diaphragm has been released from latch 187), or in other words-since chamber compartment 152b is at atmospheric pressure-that valve 167 closes only when pressure in chamber compartment 152a falls substantially below a level at which valve 142 is maintained open, so that as long as normal supply of chlorine to the system continues, valve 167 does not close. Thus in one illustrative example of the described valve unit, the biasing forces acting on the stem and diaphragm 154 are such that once valve 142 opens, it is maintained open as long as the pressure in chamber compartment 152a is a vacuum in a range between minus 19 and minus 26 inches of water, this being the normal vacuum in compartment 152a during supply of chlorine to the system in such example; but valve 167 closes only when pressure in compartment 152a falls to a vacuum of about minus 40 inches of water.

As hereinafter further explained, the valve 167 does not close during normal continuous operation of the system with automatic opening of one valve unit (for discharge of chlorine from the cylinder connected thereto) upon exhaustion of the cylinder connected to the other valve unit; and even when an exhausted cylinder is disconnected from a valve unit for replacement, the valve 167 of that unit does not close if chlorine is continuing to discharge into the system through the other valve unit. However, the valves 167 of the valve units do close if both cylinders become exhausted before either is replaced, or if the valve outlets 14 and 15 of both cylinders are shut off. Valve 167 is also operative to effect closure of the valve unit upon exhaustion of its associated cylinder if the valve unit is used in a system supplied by only a single cylinder, again as further explained below.

As a further particular feature of the invention, in combination with the valve 167, a bypass check valve 188 is provided in the valve unit for controlling flow of gas through a passage 189 that extends between the passage 156 and chamber portion 1520, opening into passage 156 at a locality intermediate the two valve ports 137 and 161, i.e., upstream of valve 167. This valve 188 includes a ball 190 disposed in the passage and seating on its upstream side against an O-ring 191 mounted in the passage. A helical spring 192, also within the passage, biases the ball into valve-closing engagement with the O-ring. The spring is held in place by a retainer element 193 threadedly mounted in the passage 189.

As already stated, when the valve 167 is closed, the valve 142 is open, and hence gas can enter passage 156 upstream of valve 167. If the chlorine supply cylinder is detached from the valve unit, air enters the passage 156, but the pressure of the air is insufficient to overcome the biasing force of spring 192 and open bypass valve 188; hence the left-hand chamber portion 152a remains in a high vacuum condition, and valve 167 remains closed. However, when a fresh chlorine supply cylinder is connected to the valve unit, the superatmospheric pressure of chlorine in the cylinder forces chlorine into the passage 156 and builds up sufficient gas pressure therein to open the bypass valve 188, which, as stated, is accessible to the chlorine in passage 156 even though valve 167 is closed, because passage 189 opens into passage 156 upstream of valve 167. Chlorine then flows through passage 189 into chamber portion 152a, until the pressure differential acting across the diaphragm 154 is sufficiently reduced so that the biasing force of spring reopens valve 167. Thereupon, chlorine again flows into chamber 152a through passage 156 and port 161,

sufficiently relieving the pressure buildup within passage 156 (and reducing the pressure differential between that passage and chamber portion 152a,- acting across ball 190) so that the bypass valve 188 recloses, and normal operation of the value unit resumes. In this way, the bypass valve 188 provides automatic reopening of the valve unit upon reconnection of the valve unit to a charged chlorine supply cylinder, i.e., after valve 167 has closed, in particular operating circumstances when valve 167 closes and remains closed while the cylinder connected to the valve unit is replaced. However, under operating conditions in which valve 167 remains open, valve 188 remains closed and does not have any effect on the operation of the valve unit.

As stated, valve unit 17 is identical in structure and function to valve unit 18, and accordingly need not be separately described.

The operation of the described system may now be readily understood. The inlet nozzle 32 of injector 25 is connected to a suitable source (not shown) of flowing water, e.g., including a pump, and tailpiece 33 is arranged to deliver a flow of water (either directly or through connecting conduits, not shown) to a main flow or body of water to be treated. A continuous flow of water from the aforementioned source is directed through the injector unit, passing successively through nozzle 32 and tailpiece 33. This continuous flow creates suction which holds the valve 35 open and produces a condition of negative pressure or vacuum throughout the gas passages of the system 10.

Two fresh, filled chlorine supply cylinders 11 and 12 are connected to the system by mounting the valve units 17 and 18 on the respective valve outlets 14 and 15 of the cylinders. The valve outlets 14 and 15 are both opened in conventional manner, so that chlorine discharge from both cylinders is solely controlled by the two valve units. At the start of operation, the pins 178 of both valve units are pulled manually all the way to the right as seen in FIG. 1, causing the latches 187 of both valve units to hold the pressure-reducing and shutoff valves 142 closed. At this time, the yellow indicator bands 181a of both valve units are visible through the slots 183 of the two units, indicating that both cylinders are in standby condition and neither is discharging chlorine.

1n the absence of chlorine supply to the system, the suction created by the continuous flow of water through the injector unit 25 causes an increase in the pressure differential acting across the diaphragms of both valve units and very shortly overcomes the restraining force of the latch in one of the valve units (for example, unit 17), with the result that the shutoff valve of unit 17 opens and chlorine begins to discharge therethrough into the system from cylinder 11. The green band of the indicator of unit 17 becomes visible through its associated slot to show that cylinder 11 is discharging. As soon as chlorine is thus supplied to the system, the pressure differential across the diaphragm of the other valve unit (unit 18) decreases, and hence the latch of unit 18 continues to hold the shutoff valve 142 of that unit in closed position, i.e., as long as chlorine continues to be discharged from cylinder 11 through unit 17.

The chlorine gas under superatmospheric pressure in cylinder 11 is discharged through valve unit 17 at a subatmospheric pressure, owing to the pressure-reducing effect of the valve (corresponding to valve 142 in unit 18) through which the gas is released from the cylinder. From valve unit 17, the gas is drawn through conduit 21, control unit 20, conduit 26 and the injector unit 25 by the suction in the injector unit, where the gas is drawn into the flow of water advancing through the injector unit at gap 34. The flow of water leaving the injector unit through tailpiece 33 thus carries chlorine insolution, as desired for chlorinating treatment of the aforementioned major flow or body of water.

During the initial operation of the chlorinator, the operator of the system turns the knob 62 of the control unit to adjust the metering orifice 54, and hence to vary the rate of chlorine feed through the control unit, while observing the position of ball float 56 in meter tube 55, i.e., until the ball float position indicates that the gas flow rate is at the value desired. The system may then continue to function, with supply of chlorine at reduced pressure from cylinder 11 through valve unit 17, and control of chlorine flow rate in unit 20, to deliver chlorine continuously to a continuous minor flow of water through the injector unit 25, until the cylinder 11 is exhausted. in the event that water flow ceases through injector unit 25, or begins to flood that unit, valve 35 closes to prevent further discharge of chlorine from the system through the injector unit, and to prevent flooding of the system with water. Upon closure of valve 35, there is no longer any applied suction drawing the chlorine through the system, and hence system operation is halted. If there is an excessive buildup of chlorine in the system, valve 81 opens to relieve this buildup by discharging chlorine to the atmosphere from the control unit 20 through vent conduit 84.

As the discharging cylinder 1 1 becomes exhausted, the consequent dropoff in supply of chlorine to the system causes a decrease in system pressure which, communicated to valve unit 18 through conduit 22 from the control unit inlet passage 50, increases the pressure differential across the diaphragm 154 in control unit 18 sufficiently to release the diaphragm from the latch 187 and to open valve 142. The green band 181b of the indicator in valve unit 18 becomes visible through slot 183, indicating that cylinder 12 is discharging. It may be noted that the backseating valve 167 of unit 17 does not close, but instead the valve 142 remains open even though cylinder 11 is exhausted, because the system pressure communicated to the valve chamber of unit 17 is high enough (owing to the continuing supply of chlorine to the system, i.e., from cylinder 12) to prevent closure of the valve 167 of unit 17.

in this way, supply of chlorine to the system is provided in succession by the two cylinders 11 and 12, with automatic switchover from one cylinder to the other upon exhaustion of the first cylinder. System operation continues, with uninterrupted supply of chlorine to the water flow from cylinder 12, until the cylinder 12 becomes exhausted. While cylinder 12 is discharging, the exhausted cylinder 11 may be replaced with a fresh cylinder, by manually pulling the pin 178 of valve unit 17 all the way to the right so that the latch of unit 17 holds the shutoff valve of that unit closed, removing the valve unit 17 from the cylinder valve outlet 14 and remounting the valve unit 17 on the valve outlet of a fresh cylinder. While the cylinder is being replaced, the latch of unit 17 continues to hold the shutoff valve of unit 17 closed (and thereby prevents introduction of air to the system through unit 17), again owing to the fact that the continuing supply of chlorine to the system from cylinder 12 keeps the pressure differential across the diaphragm of unit 17 too low to release the diaphragm from the latch. When the cylinder 11 has been replaced, and the valve outlet of the fresh cylinder has been opened, the latch of unit 17 still holds the shutoff valve of that unit closed, preventing discharge of chlorine from the fresh cylinder while cylinder 12 is discharging. Thereafter, upon exhaustion of the cylinder 12, communication of the resultant drop in system pressure to unit 17 through conduit 21 will cause release of the diaphragm of unit 17 from its latch and open the shutoff valve of unit 17, thereby automatically initiating discharge of chlorine into the system from the fresh cylinder connected to unit 17, and continuing the uninterrupted operation of the system.

In the event that both cylinders become exhausted before either is replaced (or the valve outlets of both are closed), the backseating valves 167 of both valve units 17 and 18 close, owing to the resultant increase in pressure differential across their respective diaphragms, and the red indicator bands 181v appear through the indicator slots of the two valve units, representing the closed condition of the backseating valves. Also, in such case, indicator 102 in control unit 20 is turned into a position representing exhaustion of chlorine supply to the system. The backseating valves of the two valve units remain closed in this circumstance while the cylinders are replaced, preventing introduction of air to the system through the valve units.

It may be noted that under conditions of no chlorine supply from either cylinder, as just described, the valves 142 of the two valve units could not be kept closed by their latches 187 against introduction of air to the system during cylinder replacement (as is the case when one cylinder is replaced while the other is still discharging into the system, during continuous system operation), because the heightened pressure differential across the valve unit diaphragms resulting from complete absence of chlorine supply would overcome the restraining force of the latches and open the valves 142. Thus the valves 167, while normally performing no active function in continuous system operation with automatic switchover from an exhausted cylinder to a full cylinder, serve to close the valve units against introduction of air under the special circumstances discussed above.

The described chlorinating system is adapted to operate continuously without interruption of chlorinating treatment for replacement of an exhausted supply cylinder, since each supply cylinder may be replaced when exhausted while the other cylinder connected in the system in continuing to supply chlorine. Switchover of the system from an exhausted cylinder connected to one valve unit, to a fresh cylinder connected to the other valve unit, is effected automatically upon exhaustion of the first cylinder without attention by operating personnel.

The described arrangement enables scheduling of cylinder replacement at convenient hours. For example, in the case of a continuously operating chlorinating system that exhausts two chlorine supply cylinders during each 24-hour period, both cylinders may be replaced with a relatively short interval during each daytime period, and the system may be allowed to run through each night (without cylinder replacement during the night), while the two cylinders supply chlorine to the system in succession, switchover from one cylinder to the other being efiected automatically at night.

These advantages, it may be noted, are achieved with use of conventional supply cylinders of ordinary capacity; i.e., the prolongation of time between cylinder-replacing operations afforded by the present invention does not necessitate the use of unusually large cylinders which would be inconveniently cumbersome to handle and would represent a departure from present commercial practice in the packaging and supply of chlorine.

The control of cylinder discharge by pressure-reducing valve units mounted on the cylinders and connected through conduits to the control unit affords additional advantages. In the first place, this arrangement enables positioning of the control unit at a locality substantially removed from the chlorine supply cylinders, as may be desired for the safety and convenience of the personnel monitoring the control means; and the reduction of chlorine pressure at the cylinder outlet, effected by the valve means, avoids the difficulties (such as use of high-pressure tubing, with danger of leakage) associated with transport of chlorine gas over extended distances at the elevated pressures obtaining in conventional supply cylinders.

Further, the described arrangement facilitates cylinder replacement, because the valve unit is the only element of the system that is detached and moved in replacing a cylinder, and may be a small, relatively light, sturdy and rugged unit. If the control means, for example, were combined therewith, the structural unit mounted on the cylinder would be larger, heavier, and more cumbersome, more difficult to support on the cylinder and to remove for replacement of the cylinder; at the same time, such unit would be more susceptible to damage or misadjustment incident to such removal, owing to the relative delicacy and sensitivity of the control instrumentalities.

Moreover, the described arrangement minimizes the duplication of elements needed to effectuate operation with two cylinders in succession; i.e., only the valve units and their associated conduits need be duplicated since these are the only elements mounted on the cylinders. Both cylinders discharge through a single common control unit and injector unit, as desired for economy of cost of the system.

While a magnetic latch of the type shown at 187 in FIG. 2 is found to provide highly effective operation in achieving automatic switchover from an exhausted cylinder to a fresh cylinder, alternative types of latching means may be employed. One such modified latch is shown in FIGS. 3 and 4. These figures illustrate a valve unit 18 which is generally similar to the unit 18 shown in FIG. 2 and includes a housing body and cover 196 defining a valve chamber 197 separated into leftand right-hand chamber portions or compartments 197a and l97b (respectively maintained at system pressure and at atmospheric pressure) by a vertically extending flexible diaphragm 198. To the left of this diaphragm as seen in FIG. 3, the structure of unit 18, including cartridge 117 and the two valves 142 (not shown in FIG. 3) and 167 under control of diaphragm 198, may be identical to the corresponding portions of the unit 18 of FIG. 2.

In place of the magnetic latch 187, however, the unit 18' has a mechanical toggle latch 200 disposed in chamber portion 197b to the right of diaphragm 198. Latch 200, which acts on a shaft 201 projecting horizontally to the right from diaphragm 198, comprises an elongated flat rigid toggle bar 202 and a helical spring 203. The toggle bar 202 extends transversely of the shaft 201 across chamber portion 197b and is pivotally connected to the housing cover 196 by means of a rod 205 disposed at one side of shaft 201, so as to be pivotally movable about an axis coincident with the rod axis and perpendicular to a plane containing the axis of shaft 201. A free arm 207 of toggle bar 202 projects outwardly from the rod 205 through an opening 210 in a sidewall 211 of the housing cover 196, while the other arm 212 of the toggle bar has a hole 214 through which shaft 201 passes, and terminates in a tab 215 within chamber portion 197b, tab 215 being spaced away from a housing cover sidewall 216 opposite to wall 21 l.

A fitting 218, threadedly mounted in a bore 219 through wall 216, bears a lug 220 projecting into chamber portion 197b toward the tab 215 of arm 212. The spring 203 extends between the fitting 218 and the tab-bearing extremity of the toggle bar arm 212, having an enlarged outer end surrounding and engaging the lug 220 and a smaller inner end surrounding and engaging tab 215. The lug and tab serve to restrain the respective ends of the spring against displacement relative to the fitting 218 and arm 212, and the engagement between the spring and arm 212 constitutes a toggle-type joint.

The spring 203 acts on bar 202 in such manner as to provide two stable positions of the bar. In the first stable position, arm 207 bears against the left-hand edge 221 (FIG. 3) of opening 210, being held there by a rightwardly directed force then exerted by spring 203 on arm 212, and the central portion of arm 212 bears against a shoulder 222 formed on shaft 201 to the right of the arm, so as to hold the shaft and diaphragm 198 at their extreme rightward position, at which the valve 142 is closed. In the other stable position of the toggle bar 202, arm 207 is held against the right-hand edge 224 of opening 210 (as seen in FIG. 3) by a leftwardly directed force exerted by spring 203 on arm 212, and the latter arm is displaced leftwardly from the shoulder 222 to permit valve-opening leftward movement of shaft 201 and diaphragm 198. As the toggle bar moves from either of these stable positions through the midpoint of its excursion across opening 210, the spring 203 provides a toggle action urging the arm into the other stable position.

The described latch 200 functions in much the same manner as latch 187 to keep the valve 142 of unit 18 closed during discharge of chlorine through the other valve unit of the chlorinating system, but to release the valve control diaphragm 198 for opening of the valve 142 automatically in response to a drop in system pressure representative of exhaustion of the supply cylinder connected to the other valve unit. At the start of system operation, the latch is actuated by manually moving arm 207 (which is accessible through opening 210) leftwardly until it bears against the left-hand edge 221 of opening 210, so that arm 212 engages the shaft shoulder 222 and forces the shaft and diaphragm 198 to the right, into a position at which the valve 142 of unit 18' is closed. The pressure differential acting across diaphragm 198 urges the diaphragm to the left, but the force of spring 203 acting on toggle bar 202 maintains the toggle bar in its position keeping valve 142 closed, as long as chlorine is discharging into the system from the supply cylinder connected to the other valve unit of the system. However, when the latter supply cylinder becomes exhausted, the resultant decrease in system pressure communicated to chamber 197a of valve unit 18 increases the pressure differential across diaphragm 198; the force of this increased pressure differential, transmitted to the toggle bar arm 212 through the shaft shoulder 222, overcomes the force of spring 203 and pivotally moves the toggle bar into position shown in FIG. 3, releasing the shaft 201 and diaphragm 198 for leftward, valve-opening movement. With the valve 142 of unit 18 open, chlorine discharges into the system therethrough, from the cylinder connected to unit 18'.

In FIG. 10, there is shown a modified chlorinating system embodying the invention and generally similar to the system of FIG. 1, but arranged to feed chlorine to two separate flows of water, for simultaneous chlorinating treatment of such flows. As in the system of FIG. 1, the system of FIG. includes a pair of pressure-reducing and shutoff valve units 17 and 18 respectively mounted on the valve outlets 14 and 15 of a pair of chlorine supply cylinders l l and 12; a control unit 20, connected to the valve units by conduits 21 and 22, and feeding chlorine from its outlet 23 through conduit 26; and an injector unit 25, receiving chlorine through conduit 26.

The control unit of the FIG. 10 system is essentially identical in structure to that shown in FIGS. 5-9 but includes a gas outlet 226 from its chlorine inlet passage 50. From this outlet, gas is led through a conduit 228 to the gas inlet 229 of a second control unit 230. The second control unit 230 is similar to control unit 20 already described in providing a continuous passage for gas flow, with an externally visible flow meter, an adjustable metering orifice, and a valve for controlling pressure drop across the orifice, disposed in that passage to be successively traversed by the gas flowing therethrough. From unit 230, the gas is led through an outlet 232 and thence through conduit 234 to a second injector 236 which may be identical to the injector described above.

In this system, separate minor flows of water are conducted through the two injectors 25 and 236, and chlorine gas is introduced simultaneously to both flows within the respective injector units. Chlorine, from whichever of the two cylinders 11 and 12 happens to be discharging, is delivered to the inlet passage of the control unit 20 and within that passage, upstream of the flow meter and metering orifice of unit 20, this flow of chlorine gas is divided. A portion of the flow passes through the control and metering instrumentalities of'unit 20 to the injector unit 25, while a second portion of the flow is diverted from the inlet passage of unit 20 through conduit 228 into the unit 230 and passes through the control and metering instrumentalities of unit 230 to the injector 236. Thus separate controls are provided for the' flows of chlorine to the two injectors, yet both are fed from a common supply cylinder; i.e., both injector units first receive chlorine from one cylinder, and then (upon exhaustion of the first cylinder) both units receive chlorine from the second cylinder, the valve units 17 and 18 functioning to provide automatic successive discharge of chlorine from the two cylinders 11 and 12 in the manner already described with reference to the system of FIG. 1. Since all of the chlorine is initially delivered to the inlet passage of the control unit 20, which communicates with the supply indicator and relief valve structures of that unit, it is unnecessary to include a supply indicator or separate relief valve in the unit 230.

The structure of the valve unit of the present invention, for example as shown in FIG. 2, is also adaptable to use in systems wherein chlorine is supplied from only a single cylinder, and in such case the automatic latch may be omitted. The spring 145 serves to hold the pressure-reducing and shutoff valve 142 closed, preventing discharge of chlorine from the cylinder on which the unit is mounted, until suction is developed by flow of water through the injector unit of the system. This suction then creates a pressure differential across diaphragm 154 that opens valve 142 against the biasing force of spring 145, effecting discharge of chlorine into the system at reduced pressure. Upon exhaustion of the supply cylinder, the further reduction in pressure in chamber compartment 1520 (resulting from cessation of chlorine flow into the system) moves the diaphragm 154 further leftward to close valve 167. The valve unit may then be removed from the exhausted cylinder and mounted on a fresh cylinder without danger that air will be introduced into the system. Once the valve outlet of the fresh cylinder is opened, the pressure of chlorine gas discharging through that valve outlet opens the bypass valve 188 to introduce chlorine to chamber compartment 152a thereby to effect a rightward movement of diaphragm 154, opening valve 167 for resumption of normal supply of chlorine to the system through the valve unit.

It will be understood that while the bypass valve 188 is normally inactive during use of the valve unit in a system having two valve units (respectively mounted on two supply cylinders) with latching means providing automatic switchover of the system from one supply cylinder to another, the bypass valve is especially advantageous for use of the valve unit in a system connected to a single supply cylinder as just described; hence the provision of this bypass valve 188 in a valve unit according to the invention contributes to the versatility of the unit in enabling its advantageous use in systems having either one or two supply cylinders and valve units.

We claim:

l. A system for supplying gaseous material to a liquid from cylinders containing said gaseous material at elevated pressure, comprising a. injector means for introducing a flow of said gaseous material to a flow of said liquid;

b. control means for delivering a flow of said gaseous material to said injector means, said control means defining a gas flow passage and including means disposed in said passage for controlling the rate of gas flow therethrough;

c. a pair of pressure-reducing and shutoff valve means, respectively adapted to be connected to a pair of said cylinders, for controlling discharge of gaseous material into the system from said cylinders, each of said valve means being closable to shut off discharge of gaseous material from the cylinder to which it is connected and being openable to effect discharge of gaseous material therefrom at a pressure lower than said elevated pressure, said valves being separately and successively openable to supply gaseous material to said system from said pair of cylinders in succession; and

d. a pair of conduits for said gaseous material, respectively connecting said pair of valve means to said control means passage upstream of said flow rate controlling means, said conduits together with said control means and said injector means defining a continuous confined gas flow path extending from said pair of valve means through said injector means;

c. said injector means including liquid passage means, having a lateral opening communicating with said gas flow path, for conducting said flow of liquid past said lateral opening in such manner as to create suction at said lateral opening for drawing said gaseous material from either one of said valve means along said gas flow path and into said flow of liquid through said lateral opening; and

f. each of said valve means including i. a displaceable valve member for opening and closing the valve means;

ii. a pressure-sensitive movable element acting on the valve member for displacing the valve member in correspondence with movement of said element between a position in which said member closes the valve means and a disposition in which the valve means is open, said element being exposed to, and movable toward said open disposition in response to decrease in, pressure within said gas flow path; and

iii. latching means exerting on said element a finite restraining force opposing movement of said element toward said open disposition, for holding said element in said closed position, said latching means releasing said element for movement thereof to said open disposition upon decrease in said last-mentioned pressure to a reduced value representative of substantial absence of discharge of gaseous material through the other of said valve means.

2. A system as defined in claim 1, wherein said element comprises a flexible pressure-sensitive diaphragm having opposite sides exposed to pressure within said gas flow path and a substantially higher constant pressure, respectively, so that pressure differential across said diaphragm exerts thereon a force which increases with decrease in pressure within said gas flow path, and which urges said diaphragm toward said open disposition, said pressure differential force opposing said finite restraining force of said latching means and becoming greater than said restraining force upon decrease of pressure in said gas flow path to said reduced value.

3. A system as defined in claim 2, wherein said latching means comprises a pair of latch members respectively carried by said diaphragm and mounted in a fixed position, one of said latch members being a body of magnetic material and the other being a magnet disposed to attract said one latch member in such direction as to exert on said diaphragm central portion a restraining force opposed in direction to said pressure differential force.

4. A system as defined in claim 2, wherein said latching means includes a first member pivotally movable about a fixed axis between two different angular orientations, resilient means bearing against a fixed support and engaging said first member to form a toggle joint therewith for exerting on said first member said finite restraining force resiliently holding said first member in either of said two angular orientations, and a second member carried by said diaphragm and engageable by said first member when said first member is in one of said angular-orientations, for holding said diaphragm in its closed position, and for transmitting to said first member the pressure differential force acting on said diaphragm in a direction urging said first member toward the other of said angular orientations against the finite restraining force of said resilient means, said second member being released, upon movement of said first member to said other angular orientation, for movement of said diaphragm to its open disposition.

5. A system for supplying gaseous material to a liquid from cylinders containing said gaseous material at elevated pressure, comprising a. injector means for introducing a flow of said gaseous material to a flow of said liquid;

b. control means for delivering .a flow of said gaseous material to said injector means, said control means defining a gas flow passage and including means disposed in said passage for controlling the rate of gas flow therethrough;

c. a pair of pressure-reducing and shutoff valve means, respectively adapted to be connected to a pair of said cylinders, for controlling discharge of gaseous material into the system from said cylinders, each of said valve means being closable to shut off discharge of gaseous material from the cylinder to which it is connected and being openable to effect discharge of gaseous material therefrom at a pressure lower than said elevated pressure, said valves being separately and successively openable to supply gaseous material to said system from said pair of cylinders in succession; and

d. a pair of conduits for said gaseous material, respectively connecting said pair of valve means to said control means passage upstream of said flow rate controlling means, said conduits together with said control means' and said injector means defining a continuous confined gas flow path extending from said pair of valve means through said inector means;

e. said injector means including liquid passage means, hav ing a lateral opening communicating with said gas flow path, for conducting said flow of liquid past said lateral opening in such manner as to create suction at said lateral opening for drawing said gaseous material from either one of said valve means along said gas flow path and into said flow of liquid through said lateral openings; and

f. each of said valve means comprising:

'. structure defining a valve chamber, a valve passage for conducting gaseous material to said chamber from the cylinder to which the valve means is connected and having a valve seat, and an outlet passage for conducting gaseous material from said chamber to the conduit to the valve means;

ii. a valve member supported within said structure for guided movement into and away from passage-closing engagement with said valve seat, said valve member and valve seat together constituting a valve for shutting off flow of gas through said valve passage when closed and reducing the pressure of gas flowing through said passage when open;

iii. a flexible diaphragm extending across said chamber, having a movable central portion and dividing said chamber into two compartments, said valve and outlet passages both opening into one of said compartments for communication of pressure within said gas flow path to said one compartment, and the other of said compartments communicating with a source of substantially constant higher pressure, so that pressure differential across said diaphragm exerts thereon a force which increases with decrease in pressure within said gas flow path, and which urges said diaphragm central portion toward said one compartment;

iv. means for resiliently biasing said valve member into engagement with said valve seat;

v. means for transmitting movement of said diaphragm central portion to said valve member to move said valve member away from engagement with said valve seat in correspondence with movement of said diaphragm central portion toward said one compartment; and

vi. latching means for exerting on said diaphragm central portion a finite restraining force opposing said pressure differential force to hold said diaphragm central portion away from said one compartment, said pressure differential force becoming greater than said restraining force and releasing said diaphragm central portion from said latching means for valve-opening movement toward said one compartment, upon decrease in pressure in said one compartment to a reduced value representative of substantial absence of discharge of gaseous material through the other of said valve means.

6. A system as defined in claim 5, wherein each of said valve means further includes a. a second valve positioned in said valve passage downstream of said valve seat and controlled by said diaphragm central portion so as to close said valve passage upon movement of said diaphragm central portion toward said one compartment, beyond the position in which said diaphragm central portion effects valve-opening displacement of said valve member;

b. passage means providing a path for gas flow between said one compartment and a locality in said valve passage intermediate said second valve and said valve seat, for bypassing said second valve; and

c. check valve means for controlling gas flow through said passage means and including a valve element resiliently biased in an upstream direction into a position closing said passage means but displaceable, to open said passage means, by elevation in gas pressure within said valve passage.

7. A system for supplying gaseous material from at least two containers carrying the gaseous material'at elevated pressure for delivering a flow of said gaseous material at a reduced pressure and at a regulated rate comprising:

a. a pair of valve means, respectively coupled to said two containers, for controlling discharge of gaseous material therefrom into the system, each of said valve means being closable to prevent such discharge from the container to which it is connected and being openable to permit controlled discharge of gaseous material from that container into the system at reduced pressure;

b. conduit means for connecting each of said valve means to a common downstream location in said system;

c. each of said valve means including i. a movable element for opening and closing the valve means, said element being displaceable from a closed position in which the valve means is closed to an open disposition in which the valve means is open for controlled discharge of gaseous material therethrough as aforesaid at a pressure reduced to a substantially constant predetermined level,

ii. pressure-sensitive means responsive to variations in pressure in said conduit means for displacing said movable element between said closed position and said open disposition in correspondence with changes in pressure in said conduit means, said pressure-sensitive means being adapted to urge said movable element from said closed position toward said open disposition in response to decrease in pressure in said conduit means, and

iii. means constituting a latch cooperating with and acting when set to hold said pressure sensitive means in valve closing disposition until the downstream pressure in said conduit means falls below a predetermined abnormally reduced level;

. the latch means of the respective valve means being unlatched when the downstream pressure falls below the predetermined abnormally reduced level so that gaseous material will be delivered successively from one container at a time until depletion thereof and then automatically transferred to be supplied from the other of said two containers for delivery at the same constant predetermined reduced level until both of said two containers are exhausted.

8. A system as defined in claim 7, including control means communicating with each of said valve means and with said conduit means for regulating the rate of flow of said gaseous material from each of said valve means to said downstream location.

9. A system as defined in claim 8, wherein the downstream pressure is reduced to subatmospheric levels.

10. A system as defined in claim 9, wherein said movable elements are urged by said pressure-sensitive means into closed disposition when the downstream pressure drops to substantially zero as a result of depletion of all containers whereby a fresh container of gaseous material may be incorporated without introducing environmental gas into the system through the valves means.

11. Valve means for connection to each in a system of containers carrying gaseous material at elevated pressure and successively supplying from one container at a time a downstream flow of said gaseous material at a reduced pressure and regulated rate to a common delivery point, comprising:

a. a valve body including means for coupling said body to one of said containers;

b. a valve in said body for controlling discharge of gaseous material from said one container into the system, said valve being closable to prevent such discharge from the container and being openable to permit controlled discharge of gaseous material from the container into the system at reduced pressure; c. conduit means for connecting said valve body to a common downstream system location;

element being displaceable from a closed position in which the valve is closed to an open disposition in which the valve is open for controlled discharge of gaseous material therethrough as aforesaid at a pressure reduced to a substantially constant predetermined level;

e. pressure-sensitive means response to variations in pressure in said conduit means for displacing said movable element between said closed position and said open disposition in correspondence with changes in pressure in said conduit means, said pressure-sensitive means being adapted to urge said movable element from said closed position toward said open disposition in response to decrease in pressure in said conduit means, and

. latch means cooperating with and acting when set to retain said pressure sensitive means in a position at which the valve is held closed until the downstream pressure in said conduit means falls below a predetermined abnormally reduced level;

g. the latch means being unlatched when the downstream pressure falls below the predetermined abnormally reduced level so that gaseous material will be delivered from one container in the system at a time until depletion thereof and then automatically transferred to another container for delivery at the same predetermined constant reduced level until all containers are exhausted.

12. Valve means as defined in claim 11, adapted for use where the downstream reduced pressure is at subatmospheric levels.

13. Valve means as defined in claim 11, wherein said pressure-sensitive means urges said movable element into a second closed position when the downstream pressure drops to substantially zero as a result of depletion of all the containers in the system.

14. Valve means as defined in claim 11, wherein said latch means comprises a pair of latch members respectively carried by said pressure-sensitive means and mounted in said valve body, one of said latch members being a body of magnetic material and the other being a magnet disposed to attract said one latch member in such direction as to exert on said pressure-sensitive means a restraining force opposed in direction to force exerted on said pressure-sensitive means by reduction in the downstream pressure.

15. Valve means as defined in claim 11, wherein said latch means includes a first member mounted in said valve body so as to be pivotally movable about a fixed axis between two different angular orientations, resilient means bearing against a portion of said valve body and engaging said first member to form a toggle joint therewith for exerting on said first member a finite restraining force resiliently holding said first member in either of said two angular orientations, and a second member carried by said pressure-sensitive means and engageable by said first member when said first member is in one of said angular orientations, for holding said pressure-sensitive means in a position at which the valve is held closed, and for transmitting to said first member force acting on said pressuresensitive means in a direction urging said first member toward the other of said angular orientations against the finite restraining force of said resilient means, said second member being released, upon movement of said first member to said other angular orientation, for movement of said pressure-sensitive means to displace said movable element from said closed position.

16. Valve means as defined in claim 11, including means for resiliently biasing said movable element into said closed position.

. a movable element for opening and closing the valve, said 

2. A system as defined in claim 1, wherein said element comprises a flexible pressure-sensitive diaphragm having opposite sides exposed to pressure within said gas flow path and a substantially higher constant pressure, respectively, so that pressure differential across said diaphragm exerts thereon a force which increases with decrease in pressure within said gas flow path, and which urges said diaphragm toward said open disposition, said pressure differential force opposing said finite restraining force of said latching means and becOming greater than said restraining force upon decrease of pressure in said gas flow path to said reduced value.
 3. A system as defined in claim 2, wherein said latching means comprises a pair of latch members respectively carried by said diaphragm and mounted in a fixed position, one of said latch members being a body of magnetic material and the other being a magnet disposed to attract said one latch member in such direction as to exert on said diaphragm central portion a restraining force opposed in direction to said pressure differential force.
 4. A system as defined in claim 2, wherein said latching means includes a first member pivotally movable about a fixed axis between two different angular orientations, resilient means bearing against a fixed support and engaging said first member to form a toggle joint therewith for exerting on said first member said finite restraining force resiliently holding said first member in either of said two angular orientations, and a second member carried by said diaphragm and engageable by said first member when said first member is in one of said angular orientations, for holding said diaphragm in its closed position, and for transmitting to said first member the pressure differential force acting on said diaphragm in a direction urging said first member toward the other of said angular orientations against the finite restraining force of said resilient means, said second member being released, upon movement of said first member to said other angular orientation, for movement of said diaphragm to its open disposition.
 5. A system for supplying gaseous material to a liquid from cylinders containing said gaseous material at elevated pressure, comprising a. injector means for introducing a flow of said gaseous material to a flow of said liquid; b. control means for delivering a flow of said gaseous material to said injector means, said control means defining a gas flow passage and including means disposed in said passage for controlling the rate of gas flow therethrough; c. a pair of pressure-reducing and shutoff valve means, respectively adapted to be connected to a pair of said cylinders, for controlling discharge of gaseous material into the system from said cylinders, each of said valve means being closable to shut off discharge of gaseous material from the cylinder to which it is connected and being openable to effect discharge of gaseous material therefrom at a pressure lower than said elevated pressure, said valves being separately and successively openable to supply gaseous material to said system from said pair of cylinders in succession; and d. a pair of conduits for said gaseous material, respectively connecting said pair of valve means to said control means passage upstream of said flow rate controlling means, said conduits together with said control means and said injector means defining a continuous confined gas flow path extending from said pair of valve means through said injector means; e. said injector means including liquid passage means, having a lateral opening communicating with said gas flow path, for conducting said flow of liquid past said lateral opening in such manner as to create suction at said lateral opening for drawing said gaseous material from either one of said valve means along said gas flow path and into said flow of liquid through said lateral openings; and f. each of said valve means comprising: i. structure defining a valve chamber, a valve passage for conducting gaseous material to said chamber from the cylinder to which the valve means is connected and having a valve seat, and an outlet passage for conducting gaseous material from said chamber to the conduit to the valve means; ii. a valve member supported within said structure for guided movement into and away from passage-closing engagement with said valve seat, said valve member and valve seat together constituting a valve for shutting off flow of gas through said valve passage when closed and rEducing the pressure of gas flowing through said passage when open; iii. a flexible diaphragm extending across said chamber, having a movable central portion and dividing said chamber into two compartments, said valve and outlet passages both opening into one of said compartments for communication of pressure within said gas flow path to said one compartment, and the other of said compartments communicating with a source of substantially constant higher pressure, so that pressure differential across said diaphragm exerts thereon a force which increases with decrease in pressure within said gas flow path, and which urges said diaphragm central portion toward said one compartment; iv. means for resiliently biasing said valve member into engagement with said valve seat; v. means for transmitting movement of said diaphragm central portion to said valve member to move said valve member away from engagement with said valve seat in correspondence with movement of said diaphragm central portion toward said one compartment; and vi. latching means for exerting on said diaphragm central portion a finite restraining force opposing said pressure differential force to hold said diaphragm central portion away from said one compartment, said pressure differential force becoming greater than said restraining force and releasing said diaphragm central portion from said latching means for valve-opening movement toward said one compartment, upon decrease in pressure in said one compartment to a reduced value representative of substantial absence of discharge of gaseous material through the other of said valve means.
 6. A system as defined in claim 5, wherein each of said valve means further includes a. a second valve positioned in said valve passage downstream of said valve seat and controlled by said diaphragm central portion so as to close said valve passage upon movement of said diaphragm central portion toward said one compartment, beyond the position in which said diaphragm central portion effects valve-opening displacement of said valve member; b. passage means providing a path for gas flow between said one compartment and a locality in said valve passage intermediate said second valve and said valve seat, for bypassing said second valve; and c. check valve means for controlling gas flow through said passage means and including a valve element resiliently biased in an upstream direction into a position closing said passage means but displaceable, to open said passage means, by elevation in gas pressure within said valve passage.
 7. A system for supplying gaseous material from at least two containers carrying the gaseous material at elevated pressure for delivering a flow of said gaseous material at a reduced pressure and at a regulated rate comprising: a. a pair of valve means, respectively coupled to said two containers, for controlling discharge of gaseous material therefrom into the system, each of said valve means being closable to prevent such discharge from the container to which it is connected and being openable to permit controlled discharge of gaseous material from that container into the system at reduced pressure; b. conduit means for connecting each of said valve means to a common downstream location in said system; c. each of said valve means including i. a movable element for opening and closing the valve means, said element being displaceable from a closed position in which the valve means is closed to an open disposition in which the valve means is open for controlled discharge of gaseous material therethrough as aforesaid at a pressure reduced to a substantially constant predetermined level, ii. pressure-sensitive means responsive to variations in pressure in said conduit means for displacing said movable element between said closed position and said open disposition in correspondence with changes in pressure in said conduit means, said pressure-sensitive means being adapted to urge said movable eleMent from said closed position toward said open disposition in response to decrease in pressure in said conduit means, and iii. means constituting a latch cooperating with and acting when set to hold said pressure sensitive means in valve closing disposition until the downstream pressure in said conduit means falls below a predetermined abnormally reduced level; c. the latch means of the respective valve means being unlatched when the downstream pressure falls below the predetermined abnormally reduced level so that gaseous material will be delivered successively from one container at a time until depletion thereof and then automatically transferred to be supplied from the other of said two containers for delivery at the same constant predetermined reduced level until both of said two containers are exhausted.
 8. A system as defined in claim 7, including control means communicating with each of said valve means and with said conduit means for regulating the rate of flow of said gaseous material from each of said valve means to said downstream location.
 9. A system as defined in claim 8, wherein the downstream pressure is reduced to subatmospheric levels.
 10. A system as defined in claim 9, wherein said movable elements are urged by said pressure-sensitive means into closed disposition when the downstream pressure drops to substantially zero as a result of depletion of all containers whereby a fresh container of gaseous material may be incorporated without introducing environmental gas into the system through the valves means.
 11. Valve means for connection to each in a system of containers carrying gaseous material at elevated pressure and successively supplying from one container at a time a downstream flow of said gaseous material at a reduced pressure and regulated rate to a common delivery point, comprising: a. a valve body including means for coupling said body to one of said containers; b. a valve in said body for controlling discharge of gaseous material from said one container into the system, said valve being closable to prevent such discharge from the container and being openable to permit controlled discharge of gaseous material from the container into the system at reduced pressure; c. conduit means for connecting said valve body to a common downstream system location; d. a movable element for opening and closing the valve, said element being displaceable from a closed position in which the valve is closed to an open disposition in which the valve is open for controlled discharge of gaseous material therethrough as aforesaid at a pressure reduced to a substantially constant predetermined level; e. pressure-sensitive means response to variations in pressure in said conduit means for displacing said movable element between said closed position and said open disposition in correspondence with changes in pressure in said conduit means, said pressure-sensitive means being adapted to urge said movable element from said closed position toward said open disposition in response to decrease in pressure in said conduit means, and f. latch means cooperating with and acting when set to retain said pressure sensitive means in a position at which the valve is held closed until the downstream pressure in said conduit means falls below a predetermined abnormally reduced level; g. the latch means being unlatched when the downstream pressure falls below the predetermined abnormally reduced level so that gaseous material will be delivered from one container in the system at a time until depletion thereof and then automatically transferred to another container for delivery at the same predetermined constant reduced level until all containers are exhausted.
 12. Valve means as defined in claim 11, adapted for use where the downstream reduced pressure is at subatmospheric levels.
 13. Valve means as defined in claim 11, wherein said pressure-sensitive means urges said movable element into a second closed positioN when the downstream pressure drops to substantially zero as a result of depletion of all the containers in the system.
 14. Valve means as defined in claim 11, wherein said latch means comprises a pair of latch members respectively carried by said pressure-sensitive means and mounted in said valve body, one of said latch members being a body of magnetic material and the other being a magnet disposed to attract said one latch member in such direction as to exert on said pressure-sensitive means a restraining force opposed in direction to force exerted on said pressure-sensitive means by reduction in the downstream pressure.
 15. Valve means as defined in claim 11, wherein said latch means includes a first member mounted in said valve body so as to be pivotally movable about a fixed axis between two different angular orientations, resilient means bearing against a portion of said valve body and engaging said first member to form a toggle joint therewith for exerting on said first member a finite restraining force resiliently holding said first member in either of said two angular orientations, and a second member carried by said pressure-sensitive means and engageable by said first member when said first member is in one of said angular orientations, for holding said pressure-sensitive means in a position at which the valve is held closed, and for transmitting to said first member force acting on said pressure-sensitive means in a direction urging said first member toward the other of said angular orientations against the finite restraining force of said resilient means, said second member being released, upon movement of said first member to said other angular orientation, for movement of said pressure-sensitive means to displace said movable element from said closed position.
 16. Valve means as defined in claim 11, including means for resiliently biasing said movable element into said closed position. 